Protective face masks are used in a broad range of industrial and home applications that can include protecting a wearer's respiratory system from airborne particles and a full-face mask that also protects the wearer's face and eyes. Masks of this class are fitted with flexible flap valves to control the flow of air into and out of the mask. The mask is initially placed on the wearer's head and the retaining straps are adjusted as required to comfortably seal the mask against the wearer's face. The wearer then tests the integrity of the seal provided by the face mask before entering into a contaminated area or using hazardous materials by a method such as a positive pressure test.
One technique for the positive pressure testing of the integrity of the seal of the face mask is for the wearer to block the passage of air through the exhalation valve and then exhale into the mask. While the test response of individual masks can vary, a proper fitting mask should produce a high internal pressure. If the wearer feels a flow of air at one or more release points without first experiencing a significant build-up of pressure inside the mask, the fit is not proper. If the face mask seal passes the test, the wearer unblocks the exhalation valve and is ready to use the mask. When a sealing test failure occurs, the wearer must adjust the fit of the face mask and perform the test again until the test is successfully completed.
With some mask configurations, placing the palm of the hand over the exhalation valve outlet can prevent passage of air through the flap valve and the seal of the face mask respirator can be properly tested. In many instances due to the construction of the mask and exhalation valve, the testing of the integrity of the seal of the mask on the wearer cannot be reliably performed without the assistance of a separate device that temporarily seals the exhalation valve closed during the test. This is due to factors such as the placement of the exhalation valve in the facepiece respirator, the type of exhalation valve, the risk of contamination to the exhalation valve and the degree of protective clothing worn by the wearer. For example, if the wearer has also donned protective gloves, the wearer's ability to manually test the integrity of the seal of the face mask can be inhibited by the lack of tactile sensation and the inability to form an airtight seal over the exhalation valve.
In U.S. Pat. No. 5,299,448 to Maryyanek et al., a positive pressure test apparatus 10 for a facepiece respirator having a flexible flap valve is disclosed that includes a cover 12, a central bore 14 and a plunger 18. Plunger 18 includes a button portion 22 and an opposed flange portion 24 that are connected by a stem 20. Plunger 18 is positioned for movement along the central bore 14 in cover 12. Cover 12 encloses flange portion 24 and defines a plurality of vents 29. Flange portion 24 has a frusto-conical shape designed to cover the effective area of fluid communication through the exhalation valve. Flange portion 24 includes a base or sealing interface that has a diameter that is shown in FIGS. 1A, 1B and 2 as well as being described in Example 1, that is significantly larger than the diameter of central bore 14. Button 22 extends out from cover 12 in the rest position and is pushed inwardly until flush with a surface 26 of cover 12 in the depressed position.
Thus, the prior art apparatus has a rest position where the exhalation valve is open and a depressed position where flange portion 24 seals the exhalation valve. A biasing means 28 engages button portion 22 and a shoulder in central bore 14 and biases test apparatus 10 to the rest position. Flange portion 24 seals the area of the exhalation valve in the facepiece respirator when button portion 22 is depressed.
This prior art apparatus is limited by the interface between the rim of the frusto-conical flange element and the facepiece respirator to maintain a complete seal around the effective area of the exhalation valve and also by safety considerations. Maintaining the seal requires the proper angular orientation of the frusto-conical flange base relative to the exhalation valve. Depending upon the materials used in apparatus 10 and the exhalation valve, the flexing of stem 20 or cover 12 as a result of the downward pressure by the wearer to depress button 22, could angularly distort central bore 14 and cause a breach of the intended sealing interface. Further, apparatus 10 is a complex device that is dependent upon separate biasing means 28 positioned in the central bore to disengage button 22 from the depressed position, flush with the surface 26 of cover 12, to the rest position, where it projects outwardly from surface 26. Thus, if plunger 18 were to jam in the depressed position, the wearer could not manually access button 22 in order to break the seal of the exhalation valve.
It is therefore a principal object of the invention to provide an improved face mask positive pressure test sealing device that is reliable and that cannot be inadvertently locked in a sealed position.
It is another object of the invention to provide a face mask positive pressure test sealing device that can be activated when the wearer is under physically restrictive circumstances, such as when the wearer has on protective clothing and gloves.
Another object of the invention is to provide a test device that is economical to manufacture, does not require assembly and can be employed on masks of varying styles and designs.